Adjustable school-desk.



W. BURNESS, 1m

ADJUSTABLE SCHOOL DESK.

APPLICATION men NOV. 28. 1915. RENEWED MAR. 14. I918.

Patented A risg), 1918.

l/ENTOR mflz'am Burness Jr.

ADJUSTABLE SCHOOL-DESK.

reeaeoe.

Specification of Letters Patent.

Patented Apr. 39, 1912..

Application filed November 28, 1916, Serial No. 133,971. Renewed March 14:, 1918. Serial No. 222,517.

To all whom it may concern:

Be it known that I, WILLIAM BURNnss, J r,, a citizen of the United States, residing at 3828 Adair street, Los Angeles, in the county of Los Angeles and State of California, have invented new and useful Improvements in Adjustable School-Desks, of which the following is a specification;

This invention relates to a school desk and particularly pertains to means for vertically adjusting the desk and the seat thereof.

It is the principal object of this invention to provide vertical adjustment for the desk and seat portions of school desks and the like, whereby the vertical height of these portions may be readily changed in relation to the floor and to each other.

Another object is to provide an adjustment means for accomplishing the above purpose which will act in a semi-automatic manner and which may be actuated by one person without assistance as is necessary in making adjustments to most school desksin means for locking the desk in its adjusted position so that the locking members will not, under any circumstances, become disengaged and release the desk or seat.

Other objects will appear hereinafter.

The invention is illustrated, by way of example, in the accompanying drawings in which:

Figure l is a view in side elevation illustrating a desk and seat fitted with the adjustable locking device with which the present invention is concerned.

Fig. 2 is a view in side elevation drawn on an enlarged scale to more clearly illustrate the construction of the locking elements.

Fig. 3 is a view in section and elevation as seen on the line 3-8 of, Fig. 2, illustrating the manner in which the locking pawl adjustably secures the desk, and the means by which the pawl is positively locked in position.

Fig. 4 is a view in perspective illustrating the locking pawl as disassociated from its mounting.

Fig. 5 is a view in transverse section as seen on the line 5-5 of Fig. 2 and illustrates the interlocking manner in which the upright and plate are slidably held.

Referring to the drawings more particu larly, 10 indicates one of a pair of supporting uprights or pedestals upon which the desk and seat portions 11 and 12 are adjustably secured. This upright or pedestal is formed with a bolting flange 18 by which it may be firmly secured to the floor and maintain its brackets let and 15 in a perpendicular position. The bracket 1 1 is provided as a mounting for the seat portion 12 and is parallel to the bracket 15 which extends higher than the bracket 14: and furnishes a mounting for the desk 11. These brackets are engaged by slidable frame plates 16 and 17 upon which the seat and desk portions are otally mounted upon its frame plate 16 by 7 means of a swinging arm 18 for a purpose which will be readily understood.

Vertical adjustment is provided the seat and the desk portions by a mechanism which is formed in duplicate and therefore a description of one unit of this mechanism will be sufficient to describe the action by'whieh both the desk and seat are adjusted. By way of example, the vertical bracket 15 described as forming a part of each of the supporting uprights 10, is provided with a vertically extending central slot 19 formed with widened T-shaped ends 20 and 21. The longitudinal sides of the slot 19 are formed with a series of ratchet teeth 22 which eX- tend between the T-shaped end slots 20 and 21. A series of these ratchet teeth extend along each side of the slot 19 and with the teeth in horizontal alinement with each other. These teeth are formed with their square faces extending upwardly and are adapted to be engaged by stop pins 23 and 2 1 formed upon opposite sides or a locking pawl 25. This pawl is provided with a pivot pin 26 which is pivoted within a recess 27 formed in the back of the frame plate 17 from which the pawl extends through a pawl slot 28 into register with the ratchet teeth. A spring engaging lug 29 is formed integral with the pawl and disposed in the rear of the pivot pin 26 whereby it will swing outwardly into engagement with a pawl spring 30 secured to the back of the plate 17. The action of this spring upon the pawl will tend to draw the pins 23 and 24 into engagement with the ratchet teeth and cause them to ride over the ends of the ratchet teeth and become seated within the gullets thereof.

' As a means for lockingthe pins 23 and 24 in a desired position in relation to the ratchet teeth, the pawl is formed with an inwardly extending threaded stud-bolt 31 upon'which a wing-nut 32 is mounted. This nut is adapted to be screwed into engagement with the inner face of the plate 17 and thus hold the pins in a positive manner to prevent movement of the plate in relation to the upright. I I

Reference being had to Fig. 5 of the drawings, it will be seen that the plate 17 is formed with guide channels 38 and 34 within which ribs 35 and 86 of the upright extend, therebyholding the two members in sl-idable and rigid relation to each other.

.In' operation, the wing-nuts32 mounted upon the stems 31 of the pawls of the desk element to be'adjusted are first loosened so that the pawls will have freedom of movement suflicient to permit them to clear the top of the ratchet teeth. If it is desired to increase the height of the element from the floor, it is then taken by both sides and raised upwardly. This movement will cause the pawls to ride over the ratchet teeth and bear thereagainst as held by the springs 80, and will thus allow the element to be drawn to a given height and there automatically secured. The height. to which the element has been raised may be approximately determined by the audible click made by the pawls as they pass into vthe gullets of the ratchet teeth. After the element has been raised to its desired height, the wing-nut maybe again screwed into po sltion and the upright and plate held in a rigid manner against movement.

. pawls register with the slots 21.

To lower the elements, the plates are drawn upwardly until the pins of the pawls register with the widened slots 20 at the upper end of the longitudinal slot 19. The lower walls of the slots 20 are beveled and as the plates are then forced downwardly the pins 23 and 24 of the pawls will be forced beneath the uprights and will allow the plates to move downwardly until the At this point the springs 30 will force the pawls outwardly and cause them to ride over the ratchet teeth-as the plates are again drawn upwardly. The proper adjustment may then be made from the bottom of the ratehets.

Itwill thus be seen that the adjustment here provided is simple in its construction and will readily act to positively secure the desk and seat portions of a desk in a desired vertically adjusted position.

ljVhile I have shown the preferred con struction of my adjustable mechanism for school desks, it will be understood that various changes in the combination, construction and arrangement of parts may be made by those skilled in the art without departing from the spirit of my invention.

I claim:

1. In an adjustable school desk, a pedestal having a vertical track slot and ratchet teeth extending outwardly and upwardly on each side of the slot, a supporting plate having a track connection with the pedestal for sliding vertically and having a pawl slot in alinement with the track slot and having pawl pivot recesses in its inner face, and a pawl extending through the pawl slot and through the track slot and having a pivot pin in the pivot recesses and having stop pins for engaging the ratchet teeth.

2. In an adjustable school desk, a pedestal having a vertical track slot and ratchet teeth extending outwardly and upwardly on each side of the slot, a supporting plate having a track connection with the pedestal for sliding vertically and having a pawl slot in alinement with the track slot and having pawl pivot recesses in its inner face, and a pawl extending through the pawl slot and through the track slot and having a pivot pin in the pivot recesses and having stop pins for engaging the ratchet teeth, there being a lug extending inwardly from the pawl and a spring secured to the supporting plate and engaging the lug to hold the pawl in yielding position.

3. In an adjustable school desk, a pedestal having a vertical track slot and ratchet teeth extending outwardly and upwardly on each side of the slot, a supporting plate having a track connection with the pedestal for sliding vertically and having a pawl slot in alinement with the track slot and having pawl pivot recesses in its inner face, and a pawl extending through the pawl slot and through the track slot and having a pivot pin in the pivot recesses and having stop pins for engaging the ratchet teeth, there being a stud bolt extending inwardly from the pawl and a nut upon the stud bolt and engaging the inner face of the supporting plate to lock the pawl.

In testimony whereof I have signed my name to this specification.

WM. BURNESS, JR.

, Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, D. G. 

